Sanded vs Unsanded Grout: Joint Width Decides
Sanded vs unsanded cement grout compared — ANSI classes, joint-width ranges, shrinkage in wide joints, scratch risk on polished tile, and wall work.
Updated August 22, 2026
One variable settles most grout aisles: the width of the joint. The Tile Council of North America’s guidance is blunt — cementitious joints smaller than 1/8 inch generally take unsanded grout only, and joints 1/8 inch and larger take sanded grout only — and the major manufacturers’ product ranges are built around exactly that line, with unsanded products rated up to 1/8 inch and sanded products from 1/8 up to about 1/2 inch, per each bag’s specification.
The sand is structural, not decorative. Aggregate gives the cured grout body and holds it against shrinkage as the cement paste dries, which is why a wide joint filled with unsanded grout tends to shrink back, crack, and need regrouting — the manufacturers’ own stated reason for the width limits. The same sand is the liability on delicate surfaces: TCNA’s warning is that sanded grout never belongs against marble or any other surface the aggregate can scratch.
Both versions are cement grouts certified under the same ANSI umbrella — A118.6 for standard and A118.7 for high-performance cement grouts, each class sold in sanded and unsanded form — so the choice is aggregate, not chemistry. Quantity math is identical either way: the tile estimator computes grout mass from joint geometry and rounds to the bags stores actually sell.
Side by Side
| Spec | Sanded grout | Unsanded grout |
|---|---|---|
| Composition & ANSI classification context | Portland cement grout with graded sand aggregate; certified to ANSI A118.6 (standard) or A118.7 (high-performance) depending on the product line | The same cement chemistry without the sand — a finer, smoother paste; likewise certified under A118.6 or A118.7 by product, so the ANSI number describes performance class, not aggregate |
| Joint-width range servedThe 1/8″ threshold is the industry consensus line, confirmed across TCNA and major manufacturers; the governing numbers are always the specific bag’s stated range. | Joints 1/8″ and larger (TCNA guidance), with manufacturer ranges typically topping out near 1/2″ — the exact bounds are on each product’s data sheet | Joints up to 1/8″ (TCNA guidance and the category-consistent manufacturer limit) — the tight-joint specialist |
| Shrinkage & cracking in wide joints | The aggregate is the anti-shrinkage skeleton: sand carries the volume so the cement paste cures without pulling away from tile edges in wide joints | Paste-only grout shrinks as it cures — harmless in a 1/16″ joint, but in wide joints it slumps, cracks, and fails, which is precisely why manufacturers cap it at 1/8″ |
| Scratch risk on polished & delicate surfaces | The hazard case: TCNA’s warning is categorical — never against marble or any surface the sand can scratch; polished stone and some glass mosaics are exactly that | The safe hand on polished marble, honed stone, and scratch-prone glass — no aggregate, no abrasion during float and cleanup |
| Vertical-joint workability | Heavier and grittier on a wall; workable, but gravity and the float fight back in thin vertical joints | The wall favorite: stickier, creamier consistency hangs in narrow vertical joints — most wall and backsplash tile runs tight joints anyway, so the width rule and the workability preference usually agree |
| Sealing needs | Cement grout is porous: manufacturers commonly recommend a penetrating sealer after cure for stain resistance — check the product’s guidance | Same porous chemistry, same category recommendation; sealing is a cement-grout question, not a sanded-versus-unsanded one |
| Bag sizes commonly soldGrout quantity follows joint geometry: the estimator computes mass per area from tile size, joint width, and depth with a 1.6 kg/dm³ bulk-density factor, then rounds up to whole bags. | 10 lb and 25 lb bags — the sizes the tile estimator rounds grout mass into | The same 10 lb and 25 lb retail sizes; unsanded jobs at tight joints simply consume far less mass per square foot |
Which One for the Job
12×24 rectified porcelain floor at standard joints
Sanded grout
Floor joints at 1/8 inch and up sit squarely in sanded territory by both the TCNA rule and every manufacturer range, and a floor needs the aggregate’s resistance to shrinkage and traffic. Porcelain shrugs off the sand. If the design tightens rectified joints below 1/8 inch, the same rule flips the answer — or points at a high-performance A118.7 product rated for the exact width chosen.
Glass mosaic backsplash
Unsanded grout
Mosaic sheets run tight joints — unsanded width territory to begin with — and glass is a surface TCNA’s scratch warning covers: dragging aggregate across a glossy face during float and cleanup is how backsplashes get hazed. The unsanded paste also hangs better on the vertical surface. Several manufacturers make grouts specifically rated for glass tile; the product data sheet outranks the category rule.
Polished marble shower walls
Unsanded grout
This scenario stacks all three unsanded advantages: marble is TCNA’s named never-with-sand surface, wall work favors the stickier paste, and polished stone installations run tight joints. Seal per the grout manufacturer once cured, and keep the same no-aggregate logic in mind when choosing the cleaning regimen — the stone outlaws abrasives forever, not just on grout day.
Frequently Asked Questions
Why does grout come in sanded and unsanded versions at all?
Because cement paste alone cannot hold a wide joint. Sand aggregate gives cured grout its volume stability — without it, the paste shrinks as it dries, and in joints wider than about 1/8 inch that shrinkage becomes slumping and cracking, which is why TCNA and the manufacturers cap unsanded grout there. Below 1/8 inch the sand physically crowds the joint and roughens delicate tile, so the fine paste takes over. Two products, one threshold, each covering the other’s failure zone.
Will sanded grout really scratch my polished tile?
On genuinely scratch-prone surfaces, yes — the risk is the float and cleanup stage, when you are rubbing aggregate across the tile face under pressure. TCNA’s guidance names marble outright and extends to any surface the sand can scratch; polished natural stone and many glass tiles qualify, while standard glazed porcelain and ceramic generally do not. When the tile is delicate and the joint still demands sanded width, test a spare tile first or use a manufacturer product specifically rated for that surface.
Can I mix sanded and unsanded grout to split the difference?
No — TCNA is explicit that the two should never be mixed. A blend has neither product’s engineering: an uncontrolled aggregate ratio changes water demand, shrinkage behavior, and strength, and voids both bags’ certifications and instructions. If a joint width sits awkwardly at the boundary, the answer is a product rated for that width — the high-performance A118.7 lines include grouts engineered for exactly the tight-but-not-tiny range — not a bucket blend.
Does sanded or unsanded grout need sealing afterward?
Both, by the same logic: sealing is a property of cement grout, not of the aggregate. Cured cementitious grout of either kind is porous and will absorb kitchen spills and shower water, so manufacturers commonly recommend a penetrating sealer once the grout has fully cured, on the schedule the data sheet gives. The exceptions are the non-cement chemistries — epoxy and some premixed grouts — which do not take or need sealers. Follow the specific product’s cure and sealing instructions.
Try the Calculators
Sources
- TCNA grout guidance (tcnatile.com FAQ, read directly) — the 1/8″ sanded/unsanded threshold, the never-mix rule, and the marble/scratchable-surface warning
- ANSI A118.6 / A118.7 (via TCNA publications) — standard and high-performance cement grout classifications (scope only)
- Manufacturer category data in agreement: Custom Building Products Polyblend Plus (non-sanded ≤ 1/8″, A118.6; sanded 1/8″–1/2″, A118.7) and MAPEI unsanded-class width guidance — exact bounds per each product’s data sheet
- Tile estimator source (GROUT_BAG_SIZES_LB, GROUT_DENSITY_FACTOR_KG_DM3) — the mapped bag sizes and quantity-mechanics factor